Solder fluxes have been and are being used in the form of pastes, especially in the plumbing industry. The carrier bases used today are in the form of petroleum jelly (petroletta), petrolethum and natural or synthetic rosins. When the petroleum products are used with heat, they generate smoke, and they are hazardous to the user's health. They also have a number of drawbacks for achieving a good soldering joint, for example, petroleum is greasy and therefore non-wetting, petroleum and resin burn and therefore present a fire hazard, petroleum and resin (rosin) create smoke and therefore are unhealthy to breathe, they are not water washable and they leave behind a residue which enhances corrosion, and contamination of drinking water, and petroleum products, resin and rosin bases are rough on the hands of the user--a substantial health problem.
U.S. Pat. No. 736,812 (to Bormann) relates to compositions for soldering. More specifically, this reference teaches a solder composition comprising a finely powdered soft solder which has been triturated to a paste (eg. tin alloy), a deoxidizing agent (eg. one or both of zinc chloride or ammonium chloride) and a "thickening body" (eg. cellulose). This composition suffers the disadvantages discussed above because it is essentially a resin or rosin product, and being organic it also has a flash point.
U.S. Pat. No. 1,435,780 (to Wyatt) relates to a soldering composition which comprises water, zinc chloride, ammonium chloride, mercury and muriatic acid. The flux containing mercury is of course, totally undesirable because of health reasons. Because of the low ph of muriatic acid, it is therefore highly corrosive.
U.S. Pat. No. 1,775,197 (to Habif) purports to teach a composition which overcomes the disadvantages of the prior formulations which give off gases when used, which gases are detrimental to the health of the user. The formulation taught comprises a fluxing agent (eg. zinc chloride), a cleaning agent (eg. an alcohol), an adhesion agent (eg. glycerine, molasses or "any other syrupy material which will act to cause the solution to adhere to the surface to be soldered") and a dissolving agent (eg. water). The cleaning agent is intended to dissolve grease and also to serve as a thinner. The drawback with the teachings herein is that the formulation taught is a liquid. Being a liquid, the formulation is not easily retainable at the site of the soldering operation.
U.S. Pat. No. 2,493,372 (to Williams) relates to a brazing flux composition which comprises a halide or a boron-fluorine containing compound and a compound "containing only carbon, hydrogen and oxygen". This formulation is non-aqueous and non-hygroscopic in character. See column 2, line 48 to 49 of said Patent.
U.S. Pat. No. 3,912,550 (Assigned to Stannol-Lotmittelfabrik Wilhelm Paff) relates to flux compositions for solders comprising a resin-based (preferably rosin-based) carrier substance and an activating agent based on hydrohalic acid salts of organic amines having a specific formula set out in the Patent at column 2, lines 1 to 10.
U.S. Pat. No. 3,971,675 (Assigned to The Dow Chemical Company) relates to a purportedly non-fuming soldering flux composition comprising a mixture of zinc bromide and an alkali metal bromide, for example, sodium bromide, potassium bromide and lithium bromide.
U.S. Pat. No. 4,647,308 (Assigned to Copper Development Association, Inc.) relates to soldering compositions, fluxes and methods for their use. The compositions comprise copper, nickel, aluminum, chromium (optional), titanium (optional) and zinc (as the major component). The flux compositions comprise zinc chloride, ammonium chloride, tin chloride, hydrochloric acid, lithium borate (Li.sub.2 B.sub.4 O.sub.7), magnesium bromide, zinc bromide and water.
U.S. Pat. No. 4,657,589 (Assigned to McDonnell Douglas Corporation) relates to a solder cream formulation comprising lead, tin, silver and gold particles. A base which includes abietic acid, paraffin wax, 2-butoxy (ethyl) ethyl acetate, cetyl alcohol, hydrogenated castor oil, isopropyl amine and FC71 vehicle. Because paraffin wax and cetyl alcohol are both solids, the cream must be formed in association with other compounds and this formulation does not include water. Furthermore, this composition does not relate to the flux but rather relates to a solder. Thus, the said Patent relates to a combination of solder and activating ingredients not a flux per se.
It is therefore an object of this invention to provide new flux compositions which overcome the above deficiencies of the prior art formulations by providing a flux composition which is water-soluble, has no flash point and is therefore, non-flammable, is non-toxic. When heated, the flux composition does not produce toxic substances, an unpleasant smell and irritating fumes.
It is a further object of this invention to provide flux compositions which are acid-free and which provide for improved tarnish-removing capability.
It a further object of this invention to provide such compositions that lower the cohesive force of the solder and therefore help in wetting the base metal surfaces.
It is still a further object of this invention to provide such a formulation which protects and clears the base metal surfaces and which is activated when the metal surface is heated.